Vehicle seats often include a mechanism that allows them to move back and forth, for example to adjust leg room or to facilitate reclining the seat. In the event of sudden acceleration or deceleration of the vehicle, the forces acting on the seat, with or without a passenger, can cause unwanted and dangerous movement of the seat via the mechanism.
In a typical reclinable aircraft seat, the recline mechanism, which enables the movement of the seat between upright and recline position, optionally bed position, comprises a movable upper carriage coupled to a fixed lower structure that is connected to the aircraft floor structure. At any position within its full range of movement, the upper carriage may be stopped by the passenger, and must be securely retained against inadvertent movement. In the case of a manually operated recline mechanism, this may be achieved by means of a system of spring-loaded teeth and slots similar to a manual car seat adjuster. If the recline mechanism is to be operated using a motor and reduction gear system, the force required to back drive the unpowered motor is normally sufficient to prevent movement of the carriage. Except for TTL (taxi, take-off or landing), the loads that might cause the carriage to move are in the order of 1.5G-2G in a forward or aft direction. For TTL, the loads that must be sustained are 9G (static) or 16G (dynamic) in the forward direction and 1.5G in the aft direction.
Vehicle seats may also comprise an apparatus for locking the vehicle seat, and for locking the seat's movable recline carriage, to prevent the unwanted and dangerous movement of the seat, such as in the event of sudden acceleration or deceleration of the vehicle. However, such apparatuses can be prone to inappropriate locking or jamming during the normal use of the seat, for example, due to foreign objects getting lodged in the recline mechanism. Consequently, the further normal use of the seat is prevented.
It is desirable therefore to provide an apparatus for locking a vehicle seat with respect to its slide mechanism, and in particular for locking a seat's movable recline carriage with respect to a fixed lower structure, which mitigates the problems outlined above.